A fuel cell, which is a cell directly converting chemical energy produced by oxidation of electrical energy, is a novel, environment-friendly, and futuristic energy technology generating electrical energy from materials existing abundantly on earth, such as hydrogen and oxygen.
In a fuel cell stack, oxygen is supplied to a cathode, hydrogen is supplied to an anode, and an electrochemical reaction, which is a reverse reaction of electrolysis of water is performed to generate electricity, heat, and water, such that pollution is not generated and electrical energy is produced in high-efficiency.
Since the fuel cell stack does not have a limitation of a Carnot cycle which has a limitation in a heat engine of the related art, efficiency thereof may be increased to 40% or more. In addition, as described above, since the material to be discharged is only water, there is no risk of pollution, and since a mechanically operating portion is not necessary, unlike the heat engine of the related art, the fuel cell stack has various advantageous having a small size, no noise, and the like. Therefore, research into various technologies related to the fuel cell has actively progressed.
There are six kinds of fuel cell stacks, for example, a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), a polymer electrolyte membrane fuel cell (PEMFC), a direct methanol fuel cell (DMFC), an alkaline fuel cell (AFC), or the like, according to a kind of electrolyte, and they are commercialized or in planning phase.
Since each of the fuel cells has various output range, usage, and the like, a fuel cell may be selected to be appropriate for the purpose. Among the fuel cells, in the SOFC, the electrolyte is relatively easy to be position-controlled, the position of the electrolyte is fixed, such that the electrolyte is not exhausted. In addition, since the SOFC is corrosion-resistant, life-span of the material thereof is long. Therefore, the SOFC has been highlighted for distributed generation, commercial, and home powers.
Chemical reaction schemes below show an operating principle of the SOFC in the case in which oxygen is supplied to the cathode and hydrogen is supplied to the anode.Anode Reaction: 2H2+2O2−→2H2O+4e−Cathode Reaction: O2+4e−→2O2−
Here, the SOFC is generally manufactured in a stack type having a plurality of multilayered fuel cells in order to increase an output thereof. In the case in which the plurality of flat tubular fuel cells are manufactured in a stack type, a method of supplying air between each of the fuel cells and being conducted to each other is required.
However, since an empty space needs to be formed in order to supply air to the fuel cells, a contact area for conduction is decreased by the empty space.
In particular, in the case in which the fuel cell having a large area is formed, a surface thereof may frequently be uneven or bent, such that the contact area for conduction is more decreased. Therefore, a method of smoothly supplying air between the fuel cells and being conducted to each other is required.